Update service-traffic-policy.md (#31408)

* Update service-traffic-policy.md

<h3>What this PR does ?</h3>
Improve documentation.

<h3>Which issue this PR fixes ?</h3>
fixes 31403(Issue).

* Update service-traffic-policy.md

* Update service-traffic-policy.md

* Update service-traffic-policy.md

content/en/docs/concepts/services-networking/service-traffic-policy.md

@@ -9,7 +9,7 @@ weight: 45
 
 <!-- overview -->
 
-{{< feature-state for_k8s_version="v1.21" state="alpha" >}}
+{{< feature-state for_k8s_version="v1.23" state="beta" >}}
 
 _Service Internal Traffic Policy_ enables internal traffic restrictions to only route
 internal traffic to endpoints within the node the traffic originated from. The
@@ -20,9 +20,9 @@ cluster. This can help to reduce costs and improve performance.
 
 ## Using Service Internal Traffic Policy
 
-Once you have enabled the `ServiceInternalTrafficPolicy`
-[feature gate](/docs/reference/command-line-tools-reference/feature-gates/),
-you can enable an internal-only traffic policy for a
+The `ServiceInternalTrafficPolicy` [feature gate](/docs/reference/command-line-tools-reference/feature-gates/)
+is a Beta feature and enabled by default.
+When the feature is enabled, you can enable the internal-only traffic policy for a
 {{< glossary_tooltip text="Services" term_id="service" >}}, by setting its
 `.spec.internalTrafficPolicy` to `Local`.
 This tells kube-proxy to only use node local endpoints for cluster internal traffic.